dxButton updates

- Difference between txr et btn color.
- Added the default visibility to true or the parent's one if any.
utility functions updated

- shortened some of them
- Commented the table.delete (problem with table's reference)
- Added visibility functions
Added onClientDXClick and onClientDXDoubleClick

- onClientDXClick
- onClientDXDoubleClick
dxCreateButton returns dxe + text area fixed

- Forgot to return dxe before in dxCreateButton function
- Also fixed the text area width 2pxl longer (x-1 and x+w+1) to be
exactly like the CEGUI version.
- Added support for multiple lines (wordBreak)